This invention relates a rod-actuating strap control device for a strapping machine, particularly to one capable of adjusting and controlling the length or weight of packaging strap stored in a strap reserving room with quickness and stability.
Generally, a strapping machine has a strap control device provided for the strap reserving room in controlling a packaging strap of a present length to be stored in a strap reserving room and guided out for strapping an article to be strapped.
A conventional control device 10 for controlling a strap reserving length or weight, as shown in FIGS. 1 and 2, includes a balanced rod 11 and a press rod 12 fixed respectively on the opposite ends of a rotating shaft 13, which is inserted through the separating plate 21 of a strap reserving room and through a shaft sleeve 14 secured on the outer side of the separating plate 21, letting the balanced rod 11 and press rod 12 positioned respectively at the inner and the outer side of the separating plate 21. The shaft sleeve 14 is fitted around with a fixing base 15 having a support frame 151 extending outward horizontally. The support frame 151 is fixed with a micro-switch 16 on one side, and a twisting spring 17 and a stop rod 18 on the front side 152. The twisting spring 17 has its lower end extending downward to make up a hook 171 positioned beneath the bottom edge of the support frame 151 and its upper end extending horizontally to form a blocking member 172 a little above the stop rod 18, with the lower edge of the end of the press rod 12 touching and pressing on the blocking member 172 to prevent the press rod 12 from pressing directly on the press button 161 of the micro-switch 16.
In operating, as shown in FIGS. 3, 4 and 5, a strap feed device 40 is first started to guide a packaging strap 30 to move along the top edge of the balanced rod 11 and get into the strap reserving room 20, with the packaging strap 30 arranged upward orderly in a mode of overlapping at the left and the right sides of the balanced rods 11 In this case, if the total weight of the packaging strap 30 guided in the strap reserving room 20 and the overlapping tension therebetween is larger than the resilience of the blocking member 172, the balanced rod 11 will be pressed to incline downward and actuate the rotating shaft 13 to rotate and make the press rod 12 incline downward synchronously. At this time, the press rod 12 has its end edge pressing on the blocking member 172 as well as on the press button 161 of the micro-switch 16, which immediately sends out a signal to turn off the power of the strap feed device 40 to stop guiding the packaging strap into the strap reserving room 20, thus finishing work of strap controlling and reserving.
On the contrary, in case the packaging strap 30 in the strap reserving room 20 is guided out for strapping articles, the gravity of packaging strap 30 on the balanced rod 11 will vanish, and the blocking member 172 will recover its resilience to push the press rod 12 to incline upward to separate from the press button 161 of the micro-switch 16. Then, the micro-switch 16 sends out a signal to turn on the power of the strap feed device 40 to start guiding the packaging strap 30 into the strap reserving room 20 for carrying out next round of strapping.
However, in the conventional control device 10, the amount of packaging strap 30 guided and stored in the strap reserving room 20 is controlled by the resilience of the twisting spring 17. Thus, when a strapping machine is in use, the blocking member 172 of the twisting spring 17 will be repeatedly pressed for a long period of time by the press rod 12, therefore the twisting spring 17 is easy to give rise to tiredness of resilience and become loose, weakened or even damaged after used for a period of time, liable to shorten the service life of the machine and impossible to stably control the length or amount of packaging strap 30 guided and stored in the strap reserving room 20.
Besides, the resilience of the twisting spring 17 is fixed, impossible to be adjusted, and the length or amount of the packaging strap 30 stored in the strap reserving room 20 is controlled by the twisting spring 17, thus failing to meet practical needs in operation.
This invention is to offer a rod-actuating strap control device for a strapping machine, able to control the amount of packaging strap stored in a strap reserving room with great stability by operating a rod-interacting unit made of an actuating rod and a weight rod separately assembled on a rotary member and by the relative action produced among the rod-interacting unit and a press rod and a balanced rod, prolonging the service life of the machine and lowering cost for maintenance and repair.